// Copyright 2017 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <cmath>

#include "src/base/platform/platform-posix-time.h"

namespace v8 {
namespace base {

    const char* PosixDefaultTimezoneCache::LocalTimezone(double time)
    {
        if (/*std::*/isnan(time))
            return "";
        time_t tv = static_cast<time_t>(std::floor(time / msPerSecond));
        struct tm tm;
        struct tm* t = localtime_r(&tv, &tm);
        if (!t || !t->tm_zone)
            return "";
        return t->tm_zone;
    }

    double PosixDefaultTimezoneCache::LocalTimeOffset(double time_ms, bool is_utc)
    {
        // Preserve the old behavior for non-ICU implementation by ignoring both
        // time_ms and is_utc.
        time_t tv = time(nullptr);
        struct tm tm;
        struct tm* t = localtime_r(&tv, &tm);
        // tm_gmtoff includes any daylight savings offset, so subtract it.
        return static_cast<double>(t->tm_gmtoff * msPerSecond - (t->tm_isdst > 0 ? 3600 * msPerSecond : 0));
    }

} // namespace base
} // namespace v8
